Cnidaria is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in fresh water and marine environments, including jellyfish, hydroids, sea anemones, corals and some of the smallest marine parasites. Their distinguishing features are a decentralized nervous system distributed throughout a gelatinous body and the presence of cnidocytes or cnidoblasts, specialized cells with ejectable flagella used mainly for envenomation and capturing prey. Their bodies consist of mesoglea, a non-living, jelly-like substance, sandwiched between two layers of epithelium that are mostly one cell thick. Cnidarians are also some of the only animals that can reproduce both sexually and asexually.
Jellyfish, also known as sea jellies, are the medusa-phase of certain gelatinous members of the subphylum Medusozoa, which is a major part of the phylum Cnidaria.
The Portuguese man o' war, also known as the man-of-war or bluebottle, is a marine hydrozoan found in the Atlantic Ocean and the Indian Ocean. It is considered to be the same species as the Pacific man o' war or bluebottle, which is found mainly in the Pacific Ocean. The Portuguese man o' war is the only species in the genus Physalia, which in turn is the only genus in the family Physaliidae.
Box jellyfish are cnidarian invertebrates distinguished by their box-like body. Some species of box jellyfish produce potent venom delivered by contact with their tentacles. Stings from some species, including Chironex fleckeri, Carukia barnesi, Malo kingi, and a few others, are extremely painful and often fatal to humans.
Aurelia aurita is a species of the family Ulmaridae. All species in the genus are very similar, and it is difficult to identify Aurelia medusae without genetic sampling; most of what follows applies equally to all species of the genus.
The lion's mane jellyfish, also known as the giant jellyfish, arctic red jellyfish, or the hair jelly, is one of the largest known species of jellyfish. Its range is confined to cold, boreal waters of the Arctic, northern Atlantic, and northern Pacific Oceans. It is common in the English Channel, Irish Sea, North Sea, and in western Scandinavian waters south to Kattegat and Øresund. It may also drift into the southwestern part of the Baltic Sea. Similar jellyfish – which may be the same species – are known to inhabit seas near Australia and New Zealand. The largest recorded specimen was measured off the coast of Massachusetts in 1865 and had a bell with a diameter of 210 centimetres and tentacles around 36.6 m (120 ft) long. Lion's mane jellyfish have been observed below 42°N latitude for some time in the larger bays of the East Coast of the United States.
Mesoglea refers to the extracellular matrix found in cnidarians like coral or jellyfish that functions as a hydrostatic skeleton. It is related to but distinct from mesohyl, which generally refers to extracellular material found in sponges.
Pelagia noctiluca is a jellyfish in the family Pelagiidae and the only currently recognized species in the genus Pelagia. It is typically known in English as the mauve stinger, but other common names are purple-striped jelly, purple stinger, purple people eater, purple jellyfish, luminous jellyfish and night-light jellyfish. In Greek, pelagia means "(she) of the sea", from pelagos "sea, open sea"; in Latin noctiluca is the combining form of nox, "night"", and lux, "light"; thus, Pelagia noctiluca can be described as a marine organism with the ability to glow in the dark (bioluminescence). It is found worldwide in tropical and warm temperate seas, although it is suspected that records outside the North Atlantic region, which includes the Mediterranean and Gulf of Mexico, represent closely related but currently unrecognized species.
Cotylorhiza is a genus of true jellyfish from the family Cepheidae. The genus is found in the central-east Atlantic, Mediterranean, and western Indian Ocean.
Turritopsis dohrnii, also known as the immortal jellyfish, is a species of small, biologically immortal jellyfish found worldwide in temperate to tropic waters. It is one of the few known cases of animals capable of reverting completely to a sexually immature, colonial stage after having reached sexual maturity as a solitary individual. Others include the jellyfish Laodicea undulata and species of the genus Aurelia.
Gelatinous zooplankton are fragile animals that live in the water column in the ocean. Their delicate bodies have no hard parts and are easily damaged or destroyed. Gelatinous zooplankton are often transparent. All jellyfish are gelatinous zooplankton, but not all gelatinous zooplankton are jellyfish. The most commonly encountered organisms include ctenophores, medusae, salps, and Chaetognatha in coastal waters. However, almost all marine phyla, including Annelida, Mollusca and Arthropoda, contain gelatinous species, but many of those odd species live in the open ocean and the deep sea and are less available to the casual ocean observer. Many gelatinous plankters utilize mucous structures in order to filter feed. Gelatinous zooplankton have also been called Gelata.
A corpus luteum cyst or luteal cyst is a type of ovarian cyst which may rupture about the time of menstruation, and take up to three months to disappear entirely. A corpus luteum cyst does not often occur in women over the age of 50, because eggs are no longer being released after menopause. Corpus luteum cysts may contain blood and other fluids. The physical shape of a corpus luteum cyst may appear as an enlargement of the ovary itself, rather than a distinct mass-like growth on the surface of the ovary.
Cyanea is a genus of jellyfish, primarily found in northern waters of the Atlantic and Pacific Oceans and southern Pacific waters of Australia and New Zealand, there are also several boreal, polar, tropical and sub-tropical species. Commonly found in and associated with rivers and fjords. The same genus name has been given to a genus of plants of the Hawaiian lobelioids, an example of a parahomonym.
Haliclystus auricula is a stalked jellyfish or Kaleidoscope jellyfish named for its shape resembling a funnel-shaped kaleidoscope that has eight arms typically found in the Northern Hemisphere. The Staurozoan is classified within the phylum Cnidaria under the kingdom Animalia. Under its genus, H. auricula is considered the type species.
Rhizostoma pulmo, commonly known as the barrel jellyfish, the dustbin-lid jellyfish or the frilly-mouthed jellyfish, is a scyphomedusa in the family Rhizostomatidae. It is found in the northeast Atlantic, and in the Adriatic, Mediterranean Sea, Black Sea and Sea of Azov. It is also known from the southern Atlantic off the western South African coast and into False Bay. They are found typically in late summer, and early fall in increased populations which are known as blooms. This is due to higher temperatures and other environmental factors such as wind.
The helmet jellyfish, sometimes called the merchant-cap, is a luminescent, red-colored jellyfish of the deep sea, belonging to the order Coronatae of the phylum Cnidaria. It is the only species in the monotypic genus Periphylla and is one of the rare examples in Scyphozoa which life-cycle lacks a polyp stage. This species is photophobic and inhabits deeper parts of the oceans to avoid light. It may be found at the surface on dark nights.
Hyperia galba is a species of zooplankton, an amphipod in the family Hyperiidae.
Catostylus tagi is a species of jellyfish from warmer parts of the East Atlantic Ocean and since the 2000s also found in the Mediterranean Sea. It is the only member of the family Catostylidae that is found in Europe, and it is a common species in the Tagus estuary in Portugal. It has collagen in its bell which is currently being researched to see if it has biomedical uses as an intercellular matrix. The species is named after the Tagus river.
Jellyfish blooms are substantial growths in population of species under the phyla Cnidaria and Ctenophora.
Rhizostomins are proteins that are part of a pigment family only found in jellyfish in the order Rhizostomeae. These proteins are composed of a Kringle domain inserted within a cysteine-rich Frizzled domain, first identified in 2004 as the blue pigment in the barrel jellyfish Rhizostoma pulmo. It also appears in rhizostome jellyfish that do not appear blue, such as in Nemopilema nomurai, which typically presents red-brown coloration. It has been hypothesized that pigments in this family act as a sunscreen, protecting from harmful ultraviolet radiation. Natural blue pigments, such as some of the rhizostomins, are rare and there is a growing need for industrial purposes.
